In the field of the processes of production and building of tyres for vehicles wheels, there is the need to execute quality checks on the manufactured products, with the purpose of preventing defective tyres or in any case those outside design specifications from being placed on the market, and/or progressively adjusting the employed apparatuses and the machines, so as to improve and optimize the execution of the operations carried out in the production process.
Such quality checks for example include those executed by human operators, who dedicate a pre-established time on a visual and tactile examination of the tyre; if, in light of the operators own experience and sensitivity, he/she should suspect that the tyre does not comply with certain quality standards, the tyre itself is subjected to further checks, by means of a more detailed human check and/or suitable equipment, for the purpose of providing an in-depth evaluation of possible structural and/or qualitative deficiencies.
US 2010/0002244 A1 describes a technique for inspecting the surface of a tyre that is capable of discriminating, with certainty, small pieces of rubber of different quality incorporated in the surface of the tyre. A first illumination unit includes a pair of first light projectors which project the light towards an objective line, respectively from opposite sides. A second illumination unit includes a pair of second light projectors which project the light towards the objective line in a direction different from that of the first illumination unit and respectively from opposite sides. The first and second illumination unit alternately illuminate. A linear camera forms an image of a surface portion of the tyre corresponding with the objective line synchronously with the respective illumination operations of the first and second illumination unit.
US 2004/0212795 A1 describes a method for measuring a border and/or a deformation of an object. In order to improve the quality of the image, a first image is created with a first configuration of the camera and/or of the radiation source which is adapted for a first region of the image. In addition, a second image is created with a second configuration of the camera and/or of the radiation source which is adapted for a second region of the image. The two images are combined. U.S. Pat. No. 6,680,471 B2 describes an apparatus capable of uniformly illuminating the curved internal surface of a tyre by means of LED and CCD.
US 2012/0134656 A1 describes an illumination device and an inspection device for a tyre which can easily detect shape abnormalities in a produced tyre.